* Implements task cancelation
- Cancel one or all tasks.
- delete_task.sh script for invoking
- refactored to keep deleted tasks in a separate set, update tasks as
needed from registry instead of updating the stored tasks.
* Refactor cancellation, update use in vulnerabilities
* Cleanup cancellation
* Remove package_name from protomsg
* Fix test case
* fix tests
* PR feedback
Henrik Brodin